In general, when vibrating air by rubbing objects, a sound is generated, and the vibration number of times for second is a frequency, and in order to represent the frequency, a unit of hertz (Hz) is used. That is, 500 Hz is to vibrate 500 times air for 1 second.
A thick and low sound has a low frequency, and a thin and high sound has a high frequency. A frequency range is from 0 to an infinite quantity, but 15 Hz-20,000 Hz is referred to as a frequency, i.e., an audible frequency in which a human being can detect. A sound of 15 Hz or less is referred to as a low frequency, and a sound of 20,000 Hz or more is referred to as a ultrasonic wave, and an animal or an insect may hear a sound of 20000 Hz or more, and a whistle that calls a dog and an ultrasonic insect repelling device are a device using this principle.
In the whistle that calls a dog, a human being cannot hear a whistle sound and a dog hears the whistle sound and comes running. In the ultrasonic insect repelling device, a human being cannot hear a sound of the ultrasonic insect repelling device and may fall asleep, but a flea or an ant does not approach due to the sound, and a low frequency is generally used for a physical therapy.
As described above, a plurality of devices that repel an animal using acoustic waves in which a human being cannot hear and in which only an animal can hear have been introduced.
For example, there are Korean Registered Utility Model No. 289,410 (wild animal repelling device using ultrasonic wave explosive sound, filed on Jun. 8, 2002, hereinafter, referred to as Document 1) and Korean Patent Registration No. 367,810 (magpie repelling device for preventing a power failure accident, filed on Mar. 2, 2003, hereinafter, referred to as Document 2).
Document 1 relates to a wild animal repelling device that repels a wild animal by generating an ultrasonic wave explosive sound using a pressure of an explosive gas by exploding a gas at a cartridge chamber at a location such as agricultural land, an orchard, and an airfield and that includes a gas tank, an ignition device, a cartridge chamber, a nozzle, a horn, and an electronic circuit and that generates an explosive sound by supplying and exploding a gas to the cartridge chamber and that generates an ultrasonic wave explosive sound in which a wild animal dislikes with an irregular interval and an irregular magnitude by the electronic circuit by generating an ultrasonic wave explosive sound in the horn vertically attached to a cylinder by spraying an explosive gas to a nozzle of the vertically installed cylinder.
Document 2 relates to a magpie repelling device for preventing a power failure accident occurring by birds, particularly, a magpie in an electric pole of a distribution line and preventing a power failure accident that causes auditory wariness of the magpie using a warning sound in vocal characteristics of the magpie and that causes visual dislike by producing a repelling device with a red color in which the magpie hates and that generates a warning sound so as to prevent birds, particularly, a magpie from approaching an electric pole by driving a rotation driving device.
A conventional animal repelling device using acoustic waves generates an ultrasonic wave and transmits the ultrasonic wave to free space and relates to well-known technology having no technical difficulty.
A wavelength of acoustic waves gradually decreases as receding from a sound source and disappears in some moment, and this represents a principle in which when a stone drops to quiet water, a wavelength gradually decreases as receding from a point in which the stone is dropped and finally disappears. A loud sound has a long wavelength, and this is the same as a principle in which a large stone has a long wavelength. For example, there is a large difference in magnitudes of wavelengths in which a stone of 100 Kg and a stone of 1 Kg cause.
By using such a principle, a conventional animal repelling device using acoustic waves amplifies acoustic waves through a separate amplifying circuit in order to enlarge a transmitting radius after generating acoustic waves, but at this case, in an amplifying process, noise or a frequency is deformed (distorted) and thus there is a problem that acoustic waves that deviates from acoustic waves in which an animal dislikes are output.